The method involves crushing fragmented raw products in a pre-crushing unit (1) by a rotating knife system, and cooking the crushed products in a continuously feedable cooking machine (6). End processing of the cooked products is taken place in an end processing unit (12). The fragmented raw products are cut into small pieces in the pre-crushing unit before cooking such that pumpable materials are produced from the raw products. The pumpable materials are mixed and heated by direct vapor in the cooking machine. Independent claims are also included for the following: (1) a device for production of pureed, cooked foodstuffs from fragmented raw products (2) a knife system comprising a cutting set.